BS EN 12496:2013 BSI Standards Publication Galvanic anodes for cathodic protection in seawater and saline mud BS EN 12496:2013 BRITISH STANDARD National foreword This British Standard is the UK implementation of EN 12496:2013 The UK participation in its preparation was entrusted to Technical Committee GEL/603, Cathodic protection A list of organizations represented on this committee can be obtained on request to its secretary This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application © The British Standards Institution 2013 Published by BSI Standards Limited 2013 ISBN 978 580 72889 ICS 77.060 Compliance with a British Standard cannot confer immunity from legal obligations This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 June 2013 Amendments issued since publication Date Text affected BS EN 12496:2013 EN 12496 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM June 2013 ICS 77.060 English Version Galvanic anodes for cathodic protection in seawater and saline mud Anodes galvaniques pour la protection cathodique dans l'eau de mer et les boues salines Galvanische Anoden für den kathodischen Schutz in Seewasser und salzhaltigem Schlamm This European Standard was approved by CEN on 25 April 2013 CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels © 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref No EN 12496:2013: E BS EN 12496:2013 EN 12496:2013 (E) Contents Page Foreword Introduction Scope Normative references Terms and definitions 4.1 4.2 4.3 4.3.1 4.3.2 4.3.3 4.3.4 Galvanic anode materials and their properties General Anode alloy composition Electrochemical properties General Potential Current capacity Anode consumption rate 10 5.1 5.2 5.3 5.4 5.5 5.6 Anode design and acceptance criteria 10 General 10 Chemical composition 11 Physical properties 11 Electrochemical testing 11 Anode core materials 12 Cable connections 13 Annex A.1 A.2 A.3 A.4 A.5 A.5.1 A.5.2 A.5.3 A.6 A (normative) Physical tolerances for galvanic anodes 14 Anode mass 14 Anode dimensions and straightness 14 Steel core 15 Anode surface irregularities 15 Cracks in cast anodic material 15 General 15 Stand-off and flush mounting anodes 16 Bracelet anodes 16 Internal defects and destructive testing 16 Annex B (informative) Composition and performance properties for galvanic anodes 18 B.1 Aluminium alloys 18 B.1.1 Anode material 18 B.1.2 Electrochemical properties 19 B.2 Magnesium alloy 20 B.2.1 Anode material 20 B.2.2 Electrochemical properties 21 B.3 Zinc alloy 22 B.3.1 Anode material 22 B.3.2 Electrochemical properties 23 Annex C (informative) Description of various electrochemical tests 24 C.1 Free running test 24 C.2 Galvanostatic test 24 C.3 Potentiostatic test 24 C.4 Quality control testing 25 Bibliography 26 BS EN 12496:2013 EN 12496:2013 (E) Foreword This document (EN 12496:2013) has been prepared by Technical Committee CEN/TC 219 “Cathodic protection”, the secretariat of which is held by BSI This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by December 2013, and conflicting national standards shall be withdrawn at the latest by December 2013 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights According to the CEN-CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom BS EN 12496:2013 EN 12496:2013 (E) Introduction The anticipated performance, including design life, of the cast galvanic anodes for use in sea water and saline mud is determined by their composition and the quality of their manufacture This European Standard specifies the minimum requirements for the galvanic anodes quality levels and verification procedures BS EN 12496:2013 EN 12496:2013 (E) Scope This European Standard specifies the minimum requirements and gives recommendations for the chemical composition, the electrochemical properties, the physical tolerances, and the test and inspection procedures for cast galvanic anodes of aluminium, magnesium and zinc based alloys for cathodic protection in sea water and saline mud This European Standard is applicable to the majority of galvanic anodes used for seawater and saline mud applications, i.e cast anodes of trapezoidal, "D", or circular cross section and bracelet type anodes The general requirements and recommendations of this European Standard may also be applied to other anode shapes, e.g half-spherical, button, etc., which are sometimes used for seawater applications Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies EN 287-1, Qualification test of welders Fusion welding Part 1: Steels EN 12473, General principles of cathodic protection in sea water EN ISO 8044, Corrosion of metals and alloys ― Basic terms and definitions (ISO 8044) EN ISO 8501-1, Preparation of steel substrates before application of paints and related products Visual assessment of surface cleanliness Part 1: Rust grades and preparation grades of uncoated steel substrates and of steel substrates after overall removal of previous coatings (ISO 8501-1) EN ISO 15607, Specification and qualification of welding procedures for metallic materials — General rules (ISO 15607) EN ISO 15609-1, Specification and qualification of welding procedures for metallic materials — Welding procedure specification — Part 1: Arc welding (ISO 15609-1) ISO 10474:1991, Steel and steel products Inspection documents Terms and definitions For the purposes of this document, the terms and definitions given in EN ISO 8044 and EN 12473 and the following apply 3.1 acidity presence of an excess of hydrogen ions over hydroxyl ions (pH 70 °C) zinc anodes in low chloride environments can exhibit potential reversal with steel (see references [13], [23] and [24]) The actual properties for an alloy/operational condition should be determined by testing in accordance with Annex C Typical values of electrochemical properties for alloy compositions shown in Table B.5 are given in Table B.6 Table B.6 — Typical electrochemical properties of zinc anodes at ambient temperatures (5 °C – 25 °C) Alloy type Environment Closed circuit potential Ag/AgCl/seawater reference electrode Current capacity Anode consumption rate A.h/kg V Alloy Z kg/A.y Seawater -1,03 780 11,2 Marine sediment -0,99 750 11,8 Alloy Z Seawater -1,00 760 11,5 Alloy Z Seawater -1,03 780 11,2 Alloy Z Seawater -1,03 780 11,2 Marine sediment -0,98 710 12,3 NOTE The current capacity values shown are the practical capacity values for zinc alloys and incorporate an allowance for self-corrosion of the alloy No further efficiency allowance is necessary Alloys Z and Z should not be used at temperatures above 50 °C in sediments NOTE Alloy Z is a proprietary alloy that has been developed for use at elevated temperatures It is claimed that at 60 °C to 80 °C the practical capacity in seawater is 690 A.h/kg, anode consumption rate of 12,7 kg/Ay and the claimed operating potential is –0,97 V vs Ag/AgCl/seawater NOTE In marine sediment the proprietary alloy Z at 50 °C is claimed to have a practical capacity of 710 A.h/kg, anode consumption rate of 12,3 kg/A.y and operating potential of -0,95 V vs Ag/AgCl/seawater At 85 °C the claimed practical capacity is 430 A.h/kg, anode consumption rate of 20,4 kg/A.y and the claimed operating potential is -0,94 V vs Ag/AgCl/seawater 23 BS EN 12496:2013 EN 12496:2013 (E) Annex C (informative) Description of various electrochemical tests C.1 Free running test In this test, the galvanic anode is connected to a steel cathode and the polarisation behaviour is produced by the galvanostatic effect under given conditions The free running test represents a simulation of the galvanic anode in some practical situations During the test exposure, the current and the anode potential should be recorded After the exposure, the anode capacity can be calculated This test will give data on practical current capacity and anode potential The anode potential can give information on passivity The cell arrangements and exposure conditions can be critical in free-running tests An important factor is to avoid the anode current being controlled by the cathodic polarisation current (e.g if the area of the cathode sample is too small or if calcareous deposits reduce the cathodic current to a too low value, the anodic current will be reduced to near zero) With adapted cell arrangements, the free running test can be used as a screening test to give data on current capacity, anode potential and also on tendencies to passivity NOTE A method currently used for long-term testing is given in Det norske Veritas RP-B401 and detailed in its Annex C [1] C.2 Galvanostatic test In this test, the galvanic anode is exposed to a given defined constant current density During the exposure the anode potential is recorded and after the exposure the anode capacity is calculated The exposure to a constant current density on the anode does not represent a real life situation for a galvanic anode where the anode current density may vary greatly during the service life Passivation effects can therefore not be studied in this test In order to provide an indication of likely anode performance the galvanostatic test can be 2 performed at different current densities (0,003 A/m to 10 A/m ) It is important to take into account that the anode capacity will increase with increasing current density It is also important to note that at low current densities, significant scatter may be obtained which may invalidate the results NOTE Examples of galvanostatic test procedures are NACE TM0190-98 [5] for aluminium and zinc based anode alloys and ASTM G97 [22] for magnesium anode alloys NOTE These short-term tests not provide a definitive measure of long-term anode performance and are generally only used as part of a quality control procedure (as described in C.4) or as a pre-screening procedure C.3 Potentiostatic test In this test, the anode is exposed at a given defined value of potential For a practical situation an anode will operate with a relative stable potential, while the current can be expected to vary significantly However, for testing purposes the operating potential may not be sufficiently known and the set potential may give an unrealistic current output Therefore, for potentiostatic testing carried out to determine the capacity it would require experience or detailed knowledge of the operating potential Tests performed over a range of potentials represent the preferred approach The potentiostatic test is suited for establishing tendencies to passivity Such tendencies may be observed in a free-running test, but not with a galvanostatic test 24 BS EN 12496:2013 EN 12496:2013 (E) NOTE Details of potentiostatic test procedures are given in ASTM G5-94 [9] C.4 Quality control testing Short-term testing for quality control proposes may be requested to be carried out to confirm operational performance of individual anode alloy batches Short-term testing does not provide reliable data regarding long-term anode material capacity or operating potential The results from such tests should not be used for design purposes NOTE Methods currently used are described by Det norske Veritas RP-B401 Annex B [1] and NACE TM 0190-98 [5] 25 BS EN 12496:2013 EN 12496:2013 (E) Bibliography [1] Det norske Veritas Industri Norge A/S, Recommended Practice, RP B401, Cathodic protection design, Oct 2010 [2] NACE SP 0387-2006, Metallurgical and inspection requirements for cast galvanic anodes for offshore applications [3] NACE RP 0176-2003, Corrosion control of steel, fixed offshore platforms associated with petroleum production [4] NACE RP 0492-2006, Metallurgical and inspection requirements for offshore pipeline bracelet anodes [5] NACE TM 0190-98, Impressed current test method for laboratory testing of aluminium anodes [6] U.S MIL-A-18001-K (1993), Anodes, corrosion preventive, zinc [7] N.C 431 990 STCAN, Spécification technique provisoire des anodes normalisées en zinc de haute pureté [8] ASTM B418-01 (2001), Standard Specification for Cast and Wrought Galvanic Zinc Anodes [9] ASTM G5-94, Standard Reference Test Method for Making Potentiostatic and Potentiodynamic Anodic Polarization Measurements [10] ASTM F1182-90, Standard Specification for Anodes, Sacrificial Zinc Alloy [11] ASTM B843-93, Standard Specification for Magnesium Alloy Anodes for Cathodic Protection [12] Xiaoge Gregory Zhang, Corrosion and Electrochemistry of zinc, Plenum press, New York, 1996 ISBN 0-306-45334-7, Chapter 7.2.4 [13] G.K Glass and V Ashworth, “The corrosion behaviour of zinc ― mild steel galvanic cell in hot sodium bicarbonate solution”, Corrosion Science, Vol 25, pp 971 – 983, 1985 [14] Jean-Pierre Pautasso et al., Low Voltage Cathodic Protection for High Strength Steels: part 1Definition of a New Aluminium Galvanic Anode Material”; Corrosion 98, paper 725 [15] Herve Le Guyader, Valerie Debout, Anne-Marie Grolleau and Jean-Pierre Pautasso, “Low voltage aluminium anodes - Optimization of the Core-Anode Bond”, EuroCorr 2004 [16] E Lemieux, Keith E Lucas, E A Hogan and Anne-Marie Grolleau, “Performance evaluation of low voltage anodes for cathodic protection” paper 02016 presented at NACE Corrosion 2002, Denver, April 2002 (published by NACE International, Houston, Texas, USA) [17] J.N Murray, R.A Hays, S.W Smith, Jr., “Use of Indium Activated Aluminium Alloy Sacrificial Anodes in Seawater/Sewage Environments”, paper 95315, presented at NACE Corrosion 1995 (Published by NACE International, Houston, Texas, USA) [18] S.N Smith, C.F Schrieber, R.L Riley, “Supplementary Studies of the Galvalum III Anode - Exposure Time and Low Temperature”, paper 77035, presented at NACE Corrosion 1977 (Published by NACE International, Houston, Texas, USA) [19] V Ashworth, C.J Houghton, “Performance of Commercially Available Zinc and Aluminium Anodes in Sea-Bed Mud at Elevated Temperature” paper, 81112, presented at NACE Corrosion 1981 (Published by NACE International, Houston, Texas, USA) 26 BS EN 12496:2013 EN 12496:2013 (E) [20] Mark Yunovich, “Performance of high potential magnesium anodes: Factors affecting efficiency”, paper 04044, Presented at NACE 2004 (Published by NACE International, Houston, Texas, USA) [21] EN 12438, Magnesium and magnesium alloys ― Magnesium alloys for cast anodes [22] ASTM G97, Standard Test Method for Laboratory Evaluation of Magnesium Sacrificial Anode Test Specimens for Underground Applications [23] R.B Hoxeng and C.F Prutton, “Electrochemical behaviour of zinc and steel in aqueous media”, Corrosion, Vol 5, pp 330-338, 1949 [24] Robert Winston Revie, Herbert Henry Uhlig, “Corrosion and corrosion control: an introduction to Corrosion Science and Engineering”, Wiley-Interscience, 2008 [25] EN ISO 2081, Metallic and other inorganic coatings ― Electrodeposited coatings of zinc with supplementary treatments on iron or steel (ISO 2081) [26] AWS D1.1/D1.1M, Structural welding code ― Steel [27] EN ISO 1461, Hot dip galvanized coatings on fabricated iron and steel articles ― Specifications and test methods (ISO 1461) [28] EN 10025 (all parts), Hot rolled products of structural steels 27 This page deliberately left blank This page deliberately left blank NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW British Standards Institution (BSI) BSI is the national body responsible for preparing British Standards and other standards-related publications, information and services BSI is incorporated by Royal Charter British Standards and other standardization products are published by BSI Standards Limited About us Revisions We bring together business, industry, government, consumers, innovators and others to shape their combined experience and expertise into standards -based solutions Our British Standards and other 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